EP1035192A1 - Additive for a cooling lubricant - Google Patents

Abstract

Bismuth salt (I) that is derived from a linear, branched or cyclic aliphatic di-, tri- or polycarboxylic acid containing 2-60 carbon (C) atoms and has free carboxy groups available for alkali metal, ammonium or amine salt formation is used as an anticorrosion and bactericidal additive for metalworking fluids. Independent claims are also included for the following: (1) A metalworking fluid containing (I). (2) A metalworking fluid containing a bismuth salt of a linear, branched or cyclic aliphatic di-, tri- or polycarboxylic acid containing 15-40 C atoms.

Description

The invention relates to an additive for a cooling lubricant, in water-mixed state both by excellent use in the cutting or non-cutting metalworking as well as by its anti-corrosive and bactericidal properties.

Cooling lubricants are used in metal cutting and in the Metal forming for cooling and lubricating workpieces used. They are used both in machining processes as in milling, turning, drilling and grinding as even with non-cutting deformations such as rolling, deep drawing or cold extrusion. According to DIN 51385 different one between water-miscible and water-mixed Coolants. Under the term "water-mixed" is the Final state of the finished medium, usually in the form of an oil-in-water emulsion, and under "water-miscible" the cooling lubricant concentrate to understand.

Water-mixed coolants pass through the user Mix the concentrate with water.

Your main task as an emulsion solution and also in concentrated Mold in metalworking is cooling, that Lubrication and removal of the by the variety of Manufacturing operations such as turning, drilling, milling, grinding etc. incurred material removal away from the workpiece and Tool. In addition, the water-mixed coolant meets a variety of other tasks, such as keeping the clean Systems and the rust protection of machine parts.

In particular the rust protection comes with modern cooling lubricants a high priority too. Because after editing in cooling lubricants it is generally economical Reasons or because of the linkage of manufacturing processes unusual to dry the machined metal part or to be provided with a special corrosion protection. The Parts are usually placed and allowed to wet in boxes then do not rust even when wet. To check the Antirust effect is used in the development and also in the Control of water-mixed cooling lubricants in general the test with cast shavings according to DIN 51360-1 and -2 used. As has also been shown that many of the used cooling lubricants an ideal breeding ground for Microorganisms of the most different kind are and by Microbial action not only decomposed cooling lubricants smelling bad but can also be harmful to health, the task came up, an additive for a cooling lubricant to develop the anti-corrosive and bactericidal Effects combined.

This task is solved by an additive for one Cooling lubricant consisting of a bismuth salt of a linear, branched or alicyclic di-, tri- or polycarboxylic acid consisting of 2 to 60 carbon atoms and still free Carboxyl groups for the formation of alkali, ammonium or Has amine salts. Bismuth salts are particularly preferred mentioned type having 15 to 40 carbon atoms.

For the preparation of bismuth salts according to the invention are by dimerization of unsaturated fatty acids such as tall oil fatty acid obtained mixtures of acyclic and cyclic Dicarboxylic acids with an average of 36 carbon atoms as well the by-produced in the dimerization Trimer fatty acids particularly suitable. In addition, the lead Dodecylsuccinic acid and the 5- or 6-carboxy-4-hexyl-2-cyclohexene-1-octanoic acid to very good results.

Also very suitable is an additive of the abovementioned Kind, in which one or two of the remainders of the linear, branched or alicyclic di-, tri- or polycarboxylic acid of Bismuth salt by a residue of a linear or branched one Monocarboxylic acid 2 to 40 carbon atoms are replaced. When Monocarboxylic acids are in particular the stearic acid or the Oleic acid into consideration.

The said bismuth salts are considered to be an anticorrosive and bactericidal additive to coolants excellent suitable. They are added to the coolant so that the bismuth content of the ready - to - use cooling lubricant in Range of 0.05 to 5 wt .-% is.

Cooling lubricants are often based on mineral oils built up. The mineral oil qualities used are predominant Combinations of paraffinic, naphthenic and aromatic hydrocarbon compounds. In addition to the Mineral oils also have so-called synthetic lubricants such as polyalphaolefins, polyalkylene glycol and polyalkylene glycol ethers, natural ester oils and synthetic esters and their derivatives meaning.

To meet the requirements of the practice, must coolants in addition to the base oil various components contain. The most important substance groups are emulators, Anti-corrosive additives, EP additives, Antinebelzustäze, Anti-aging agents, solid lubricants and defoamers.

Emulsifiers (e.g., surfactants, petroleum sulfonates, alkali soaps, Alkanolamine soaps) stabilize the fine distribution of Oil droplets in the aqueous working fluid containing an oil-in-water emulsion represents. Put the emulsifiers an important group of additives in the water-miscible cooling lubricants.

Conventional anti-corrosion additives are intended to rust Prevent metal surfaces. Some corrosion protection additives have simultaneously emulsifying properties and find Therefore, as emulsifiers their application. Biocides should prevent the growth of bacteria and fungi. EP additives should micro-welds between metal surfaces at prevent high pressures and temperatures. Polar accessories increase the lubrication properties. Anti-aging substances ensure a long service life of the cooling lubricants.

Of the many additives used in cooling lubricants so far, bismuth compounds have hitherto only played a subordinate role. From EP-A-0 675 192 it is known to add certain bismuth compounds to lubricating oils and lubricating greases for the lubrication of bearings. The bismuth compounds serve as EP additives. These are preferably selected from naphthenates and / or carboxylates of the general formula (R-COO) ₃ Bi, in which R can denote a linear, branched or cyclic alkyl radical having 1 to 30 C atoms. In addition to bismuth naphthenates, bismuth alkylcarboxylates having 6 to 10 carbon atoms in the alkyl radical and in particular the bismuth octoate are particularly preferred.

It is also known from DE-A-196 34 733, as friction-reducing Additive for water-miscible or water-immiscible Coolants a mixture of bismuth compounds organic acids and sulfur-containing organic Use connections.

Compared with these known additives have the inventive Bismuth salts have the advantage that they are not only bactericidal, but also corrosion-reducing properties and in addition to the high demands of EP or. AW additives (extreme pressure or antiwear additives) excellent enough.

The bismuth salts of the invention may be in the aqueous Systems as sole additive or in combination with others Additives are used. Examples of such co-additives in water cycles are known corrosion inhibitors such Phosphonates, phosphonocarboxylic acids or phosphinocarboxylic acids, N-acylsarcosines, imidazolines, triethanolamine, fatty amines or Mono- or polycarboxylic acids. It has proven particularly useful the addition of monocarboxylic acids, especially isononanoic acid. Also copper passivators such as water-soluble benzotriazoles, Methylene-bis-benzotriazoles or 2-mercaptobenzothiazoles can be added. Furthermore, dispersants and Carriers, such as poly (meth) acrylic acid and its salts, hydrolyzed polyacrylonitrile, polyacrylamide and its Copolymers, Ligninsulfonsäure and their salts, starch and Starch derivatives, cellulose, alkylphosphonic acids, 1-aminoalkyl-1,1-diphosphonic acids and their salts, polymaleic acids and other polycarboxylic acids or alkali phosphates are added.

Other co-additives may be precipitants, such as alkali phosphates or alkali carbonates, oxygen scavengers such as Alkali sulfates or hydrazine, complexing agents such as Nitrilotriacetic acid or ethylenediamine tetraacetic acid and their salts, or antifoaming agents such as distearyl sebacic acid diamide, Distearyl adipamide or ethylene oxide or propylene oxide condensation products of such amides, as well as Fatty alcohols and their ethylene oxide condensation products.

a) wäßrige Konzentrate eines erfindungsgemäßen Wismutsalzes mit oder ohne einen Antiverschleißzusatz, die dann in einer Verdünnung von 1 : 50 bis 1 : 100 als Schleifflüssigkeit verwendet werden können,

b) Polyglykole, die ein Wismutsalz, Korrosionsinhibitoren und Antiverschleißmittel enthalten und die als Schneidflüssigkeit in einer Verdünnung von 1 : 20 bis 1 : 40 und als Schleifflüssigkeit in einer Verdünnung von 1 : 60 bis 1 : 80 verwendet werden können,

c) halbsynthetische Schneidöle auf ähnlicher Basis wie b), jedoch zusätzlich 10-25% eines Öls enthaltend sowie genügend Emulgator, um die Flüssigkeit beim Verdünnen transparent zu halten,

d) emulgierbare Mineralöl-Konzentrate, die außer dem Emulgator ein Wismutsalz, Antiverschleißmittel, Biocide, Antischaummittel enthalten können und die üblicherweise im Verhältnis 1 : 20 bis 1 : 50 mit Wasser verdünnt werden zu einer opaken Emulsion,

e) Produkte ähnlich d), jedoch weniger Öl und mehr Emulgator enthaltend, die bei einer Verdünnung von 1 : 50 bis 1 : 100 durchscheinende Emulsionen ergeben.

Aqueous systems used as machine fluids may be a water reducible cutting or grinding oil, such as

a) aqueous concentrates of a bismuth salt according to the invention with or without an anti-wear additive, which can then be used in a dilution of 1: 50 to 1: 100 as grinding fluid,

b) polyglycols containing a bismuth salt, corrosion inhibitors and antiwear agents which can be used as a cutting fluid at a 1:20 to 1:40 dilution and as a grinding fluid at a 1:60 to 1:80 dilution,

c) semi-synthetic cutting oils on a similar basis as b), but additionally containing 10-25% of an oil and sufficient emulsifier to keep the liquid transparent upon dilution,

d) emulsifiable mineral oil concentrates which, in addition to the emulsifier, may contain a bismuth salt, anti-wear agents, biocides, antifoaming agents and which are usually diluted in a ratio of 1:20 to 1:50 with water to give an opaque emulsion,

e) products similar to d), but containing less oil and more emulsifier, which give at a dilution of 1: 50 to 1: 100 translucent emulsions.

a) organische Säuren, deren Salze und Ester, zum Beispiel Benzoesäure, p-tert.Butylbenzoesäure, Dinatrium-sebacat, Triethanolamin-laurat, Isononansäure, das Triethanolaminsalz der p-Toluolsulfonamido-capronsäure, Natrium-N-lauroylsarcosinat oder Nonylphenoxyessigsäure;

b) stickstoffhaltige Substanzen, wie Fettsäurealkanolamide, Imidazoline, Oxazoline, Triazole oder anorganische Nitrite oder Nitrate;

c) phosphorhaltige Substanzen, beispielsweise Aminphosphate, Phosphonsäuren oder anorganische Phosphate, wie NaH₂PO₄;

d) schwefelhaltige Substanzen, beispielsweise Salze von Petroleumsulfonaten, oder heterocyclische Verbindungen wie Natrium-mercaptobenzthiazol.

Also in antifreeze or hydraulic fluids bismuth salts of the invention can be used either alone or in combination with other additives. In addition, it may also contain other corrosion inhibitors, such as

a) organic acids, their salts and esters, for example benzoic acid, p-tert-butylbenzoic acid, disodium sebacate, triethanolamine laurate, isononanoic acid, the triethanolamine salt of p-toluenesulfonamido-caproic acid, sodium N-lauroyl sarcosinate or nonylphenoxyacetic acid;

b) nitrogen-containing substances, such as fatty acid alkanolamides, imidazolines, oxazolines, triazoles or inorganic nitrites or nitrates;

c) phosphorus-containing substances, for example amine phosphates, phosphonic acids or inorganic phosphates, such as NaH ₂ PO ₄ ;

d) sulfur-containing substances, for example salts of petroleum sulfonates, or heterocyclic compounds such as sodium mercaptobenzothiazole.

The bismuth salts according to the invention may be in an aqueous alkaline Solution with a pH above 8.0 or as well flowable aqueous dispersions are used. When Dispersants are all surface-active compounds, in particular anionic and nonionic surfactants. Such dispersions may be thickened be stabilized, where as stabilizers especially modified polysaccharides of xanthan, alginate, guar or Cellulose type used. These include cellulose ethers, such as methylcellulose or carboxymethylcellulose and heteropolysaccharides. Except the dispersant and the thickening agent the dispersions of the invention can still contain additional aids, for example hydrotrope Agents such as urea or sodium xylenesulfonate; Antifreeze such as ethylene or propylene glycol, diethylene glycol, Glycerol or sorbitol; Biocides such as chloroacetamide, Formalin or 1,2-benzisothiazolin-3-one or complexing agent.

For the preparation of the dispersions it is advisable from solid bismuth salt, this sets the dispersant and the thickener and optionally the desired amount of water and other additives and stir the mixture until a flowable homogeneous dispersion is formed. The way prepared dispersions are at room temperature and at Temperatures up to 40 ° C stable for several months. You keep their fluidity and do not separate. That's for the Storage and transport of the dispersions an important Property. For the use of the dispersions it is from Advantage that they can be handled like liquids and dissolve very quickly in alkaline-aqueous systems.

The invention will be more apparent from the following examples illustrates:

Example 1: Preparation of a bismuth salt according to the invention

1 mol of Bi ₂ O ₃ was heated to about 180 ° -200 ° C with 6 moles of C ₃₆ dicarboxylic acid. After all Bi ₂ O _{3 had} dissolved, it was allowed to cool and diluted with a suitable solvent such as tall oil fatty acid. A solution of the bismuth salt was obtained, which was used for the production of the cooling lubricant.

In the same way could for the production of a Bismuth salt also the AGS acid (mixture of Adipic acid, succinic acid and glutaric acid) become. From this acid was already formed at temperatures of 130-140 ° C a corresponding bismuth salt.

Example 2: Preparation of a bismuth salt according to the invention

1 mole of Bi ₂ O ₃ was heated to about 180-200 ° C with 2 moles of stearic acid and 4 moles of a C ₃₆ dimer acid. After all the Bi ₂ O _{3 had} dissolved, it was allowed to cool and the tall oil fatty acid was diluted with a suitable solvent. A solution of the bismuth salt was obtained, which was used for the production of the cooling lubricant.

Example 3: Preparation of an oily corrosion inhibitor

60% mineral oil and 35% of a mixture consisting of one anionic and a non-ionic emulsifier and 3.5% of were prepared according to Example 1 bismuth compound mixed together and with an adjusting agent to 100% refilled. The resulting emulsion shows over control emulsions, which contain no bismuth salt, one at about a level of improved corrosion protection, determined by the Regulation of DIN 51360-2. As a measure of corrosion serve the corrosion drawings on a round filter paper, which at the action of artificially corrosive water Cast iron shavings in the presence of bismuth salts according to the invention arise.

According to this rule was placed in a beaker clear water with a total hardness of 3.58 mmol, prepared from CaCl ₂ .6H ₂ O and MgSO ₄ x 7 H ₂ O, mixed with 3% of the above-mentioned corrosion inhibitor, and with this solution, in of a Petri dish wetted on round filter gray castings wetted. After a residence time of 2 hours at room temperature, the gray castings were removed from the round filter, the round filter rinsed and dried and thus the degree of corrosion determined visually according to the table of DIN 51360-2.

In addition to the improved corrosion protection was also a Bacterial stability of the cooling lubricant observed.

Example 4 Production of an Oil-Free Cooling Lubricant

About 8% of a bismuth salt of AGS acid, 65% triethanolamine, 2% adjusting agent were dissolved in water to 100%. The obtained Solution was then added in an amount of 3% of a grinding fluid, a radiator fluid and an antifreeze as Added corrosion inhibitor. The examination of corrosion properties according to DIN 51360-2 gave corrosion degrees between 1 and 2. In addition, the coolant was bacteriostable, which in the previously known cooling lubricants only by the Addition of a special biocide was to achieve.

Example 5: Preparation of a Cooling Lubricant Emulsion

95% of a finished water-miscible cooling lubricant and 5% of the additive prepared according to Example 2 become intense mixed. The emulsion produced therefrom is finer and has all the advantages of the example 3 presented Emulsion.

Claims (7)

Additive for a cooling lubricant, characterized in that it consists of a bismuth salt of a linear, branched or alicyclic di-, tri- or polycarboxylic acid comprising 2 to 60 carbon atoms and still having free carboxyl groups to form alkali, ammonium or amine salts. An additive according to claim 1, characterized in that one or two of the radicals of the linear, branched or alicyclic di-, tri- or polycarboxylic acid of the bismuth salt are replaced by a radical of a linear or branched monocarboxylic acid having 2 to 40 carbon atoms. An additive according to claim 1 or 2, characterized in that it consists of a bismuth salt of an aliphatic, linear, branched or alicyclic di-, tri- or polycarboxylic acid having 15 to 40 carbon atoms. Use of the additive of claims 1 to 3 as Anticorrosive and bactericidal additive to cooling lubricants. Use according to claim 4, characterized in that the bismuth content of the ready-to-use cooling lubricant is in the range of 0.05 to 5 wt .-%. Use of the additive according to claims 1 to 3 alone or in admixture with mineral oils, ester oils and / or other synthetic lubricants and additives that usually used in cooling lubricants. Cooling lubricant, characterized in that it contains an additive of claims 1 to 3.